/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.apache.jk.common;

import java.io.IOException;

import org.apache.coyote.Request;
import org.apache.jk.core.JkChannel;
import org.apache.jk.core.JkHandler;
import org.apache.jk.core.Msg;
import org.apache.jk.core.MsgContext;

/**
 * Pass messages using jni
 * 
 * @author Costin Manolache
 */
public class ChannelJni extends JniHandler implements JkChannel {
	int receivedNote = 1;

	public ChannelJni() {
		// we use static for now, it's easier on the C side.
		// Easy to change after we get everything working
	}

	public void init() throws IOException {
		super.initNative("channel.jni:jni");

		if (apr == null)
			return;

		// We'll be called from C. This deals with that.
		apr.addJkHandler("channelJni", this);
		log.info("JK: listening on channel.jni:jni");

		if (next == null) {
			if (nextName != null)
				setNext(wEnv.getHandler(nextName));
			if (next == null)
				next = wEnv.getHandler("dispatch");
			if (next == null)
				next = wEnv.getHandler("request");
			if (log.isDebugEnabled())
				log.debug("Setting default next " + next.getClass().getName());
		}
	}

	/**
	 * Receives does nothing - send will put the response in the same buffer
	 */
	public int receive(Msg msg, MsgContext ep) throws IOException {
		Msg sentResponse = (Msg) ep.getNote(receivedNote);
		ep.setNote(receivedNote, null);

		if (sentResponse == null) {
			if (log.isDebugEnabled())
				log.debug("No send() prior to receive(), no data buffer");
			// No sent() was done prior to receive.
			msg.reset();
			msg.end();
			sentResponse = msg;
		}

		sentResponse.processHeader();

		if (log.isTraceEnabled())
			sentResponse.dump("received response ");

		if (msg != sentResponse) {
			log
					.error("Error, in JNI mode the msg used for receive() must be identical with the one used for send()");
		}

		return 0;
	}

	/**
	 * Send the packet. XXX This will modify msg !!! We could use 2 packets, or
	 * sendAndReceive().
	 * 
	 */
	public int send(Msg msg, MsgContext ep) throws IOException {
		ep.setNote(receivedNote, null);
		if (log.isDebugEnabled())
			log.debug("ChannelJni.send: " + msg);

		int rc = super.nativeDispatch(msg, ep, JK_HANDLE_JNI_DISPATCH, 0);

		// nativeDispatch will put the response in the same buffer.
		// Next receive() will just get it from there. Very tricky to do
		// things in one thread instead of 2.
		ep.setNote(receivedNote, msg);

		return rc;
	}

	public int flush(Msg msg, MsgContext ep) throws IOException {
		ep.setNote(receivedNote, null);
		return OK;
	}

	public boolean isSameAddress(MsgContext ep) {
		return true;
	}

	public void registerRequest(Request req, MsgContext ep, int count) {
		// Not supported.
	}

	public String getChannelName() {
		return getName();
	}

	/**
	 * Receive a packet from the C side. This is called from the C code using
	 * invocation, but only for the first packet - to avoid recursivity and
	 * thread problems.
	 * 
	 * This may look strange, but seems the best solution for the problem ( the
	 * problem is that we don't have 'continuation' ).
	 * 
	 * sendPacket will move the thread execution on the C side, and return when
	 * another packet is available. For packets that are one way it'll return
	 * after it is processed too ( having 2 threads is far more expensive ).
	 * 
	 * Again, the goal is to be efficient and behave like all other Channels (
	 * so the rest of the code can be shared ). Playing with java objects on C
	 * is extremely difficult to optimize and do right ( IMHO ), so we'll try to
	 * keep it simple - byte[] passing, the conversion done in java ( after we
	 * know the encoding and if anyone asks for it - same lazy behavior as in
	 * 3.3 ).
	 */
	public int invoke(Msg msg, MsgContext ep) throws IOException {
		if (apr == null)
			return -1;

		long xEnv = ep.getJniEnv();
		long cEndpointP = ep.getJniContext();

		int type = ep.getType();
		if (log.isDebugEnabled())
			log.debug("ChannelJni.invoke: " + ep + " " + type);

		switch (type) {
		case JkHandler.HANDLE_RECEIVE_PACKET:
			return receive(msg, ep);
		case JkHandler.HANDLE_SEND_PACKET:
			return send(msg, ep);
		case JkHandler.HANDLE_FLUSH:
			return flush(msg, ep);
		}

		// Reset receivedNote. It'll be visible only after a SEND and before a
		// receive.
		ep.setNote(receivedNote, null);

		// Default is FORWARD - called from C
		try {
			// first, we need to get an endpoint. It should be
			// per/thread - and probably stored by the C side.
			if (log.isDebugEnabled())
				log.debug("Received request " + xEnv);

			// The endpoint will store the message pt.
			msg.processHeader();

			if (log.isTraceEnabled())
				msg.dump("Incoming msg ");

			int status = next.invoke(msg, ep);

			if (log.isDebugEnabled())
				log.debug("after processCallbacks " + status);

			return status;
		} catch (Exception ex) {
			ex.printStackTrace();
		}
		return 0;
	}

	private static org.apache.juli.logging.Log log = org.apache.juli.logging.LogFactory
			.getLog(ChannelJni.class);

}
